Preheat oven to 400°F. Pierce sweet potatoes with a fork and bake directly on oven rack for 50-60 minutes until very tender.
Let sweet potatoes cool for 10 minutes, then cut in half lengthwise. Scoop out most of the flesh, leaving about 1/4 inch attached to the skin.
Mix the scooped sweet potato flesh with shredded chicken, 3/4 cup BBQ sauce, and half of the cheddar cheese. Season with salt and pepper.
Brush the sweet potato skins with melted butter and place on a baking sheet. Fill each skin generously with the chicken mixture.
Top with remaining cheddar cheese and bake for 12-15 minutes until cheese is melted. Turn on broiler for the last 2-3 minutes to get the cheese golden and bubbly.
Drizzle with remaining BBQ sauce and top with crumbled bacon, sour cream, cilantro, and green onions before serving.